This section provides background information related to the present disclosure which is not necessarily prior art.
In the design of motor vehicles the energy absorption characteristics of the vehicle structure during an impact event is an important consideration. During an impact event the vehicle occupants are subjected to crash loads that may cause severe injuries. Such crash loads are for instance the result of high acceleration during the impact event. The level of acceleration that the occupants are subjected to during an impact event is highly influenced by the stiffness of the vehicle structure. It is well known to define certain deformation zones that are adapted to absorb collision energy in order to reduce the acceleration levels experienced by the occupants and thereby reduce the risk of injuries to the occupants. By absorbing a substantial amount of collision energy the occupants are subjected to a lower acceleration during the impact event. A front subframe of a motor vehicle is normally fixed to the vehicle chassis by means of bolt joint connections.
One way of improving the occupant protection in certain crash scenarios is to release structural members during the crash. A connecting device of the above-mentioned type is known from JP-11348578 which discloses a releasable bracket device improving the shock absorbing ability of a vehicle. Two structures in the front end structure of the car are joined together by means of a bolt which is inserted in a bolt hole in the first structure and in an open and upward facing oblong hole in the second structure. When a certain crash force is exceeded in a collision the second structure is released from the first structure via a sliding movement of the bolt guided by the oblong hole. This solution has the drawback that it may result in insufficient degree of occupant protection in several crash scenarios.